KR20150067886A - Positive electrode active material for rechargable lithium battery, method for synthesis the same, and rechargable lithium battery including the same - Google Patents

Abstract

The present invention relates to a positive electrode active material for lithium secondary batteries, including cores denoted by chemical formula 1 and a coating layer located on the surface of the core wherein the coating layer comprises aluminum, aluminum oxide, lithium aluminum oxide or combinations thereof, a manufacturing method thereof and a lithium secondary battery including the same. In Li_xM_yO_2 of chemical formula 1, M is [Ni_aCo_bMn_(1-a-b)]_1-c-dZr_cW_d, x is 0.9-1.5 inclusive, y is 0.9-1.1 inclusive, a is 0.4-0.8 inclusive, b is more than 0 and not more than 0.4, c is more than 0 and not more than 0.01 and d is more than 0 and not more than 0.005.

Description

TECHNICAL FIELD [0001] The present invention relates to a positive electrode active material for a lithium secondary battery, a method for producing the same, and a lithium secondary battery including the same. BACKGROUND OF THE INVENTION [0002]

A cathode active material for a lithium secondary battery, a production method thereof, and a lithium secondary battery comprising the same.

A battery is a device that converts the chemical energy generated by an electrochemical oxidation-reduction reaction of an internal chemical substance into electrical energy. When the energy inside the battery is exhausted, the primary battery and the rechargeable secondary battery . Among them, the secondary battery can be used by charging and discharging several times by using reversible conversion between chemical energy and electric energy.

Background Art [0002] With the recent development of high-tech electronic industry, it is possible to miniaturize and lighten electronic equipments, and the use of portable electronic equipments is increasing. The need for a battery having a high energy density as a power source for such portable electronic devices has been increased, and research on lithium secondary batteries has been actively conducted.

Such a lithium secondary battery includes a positive electrode including a positive electrode active material capable of intercalating and deintercalating lithium and a negative electrode including a negative active material capable of intercalating and deintercalating lithium And the electrolyte is injected into the battery cell.

Among them, studies have been made to improve the battery characteristics by using an oxide containing various transition metals as a cathode active material. Examples of the oxide containing a transition metal include lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide and the like.

LiCoO ₂ is a superior cathode material with stable charge / discharge characteristics, excellent electron conductivity, high thermal stability and flat discharge voltage characteristics, but cobalt has a low storage capacity, high cost and toxicity to human body Therefore, development of other cathode materials is desired.

LiNiO ₂ is difficult to synthesize materials and has not been commercialized due to a problem of thermal stability, and LiMn ₂ O ₄ is partly commercialized at a low price. However, since LiMn ₂ O ₄ having a spinel structure has a theoretical capacity of about 148 mAh / g and is smaller than other materials and has a three-dimensional tunnel structure, diffusion resistance is large when lithium ions are inserted and removed, It is lower than LiCoO ₂ and LiNiO ₂ , and has poor life characteristics.

As a material capable of overcoming the above problems, much research has been conducted on materials having a layered crystal structure. Of these, lithium nickel cobalt manganese-based oxides can be used as a material having a layered crystal structure most recently exposed. This material exhibits properties such as low cost, high capacity and excellent thermal stability compared to LiCoO ₂ . However, this material has a limitation in satisfying the charging / discharging cycle characteristic, the rate characteristic, the heat stability and the like at the same time.

In order to improve the battery characteristics, attempts have been made to coat the lithium nickel cobalt manganese oxide with another transition metal such as zirconium and other metals to coat the lithium nickel cobalt manganese oxide with another metal.

Discharge characteristics and life characteristics, a method for producing the same, and a lithium secondary battery comprising the lithium secondary battery.

An embodiment of the present invention includes a metal oxide represented by the following Chemical Formula 1 and a coating layer positioned on the surface of the metal oxide, wherein the coating layer is made of a metal selected from the group consisting of aluminum, aluminum oxide, lithium aluminum oxide, A cathode active material for a secondary battery is provided.

[Chemical Formula 1]

Li _x M _y O ₂

In the above formula (1), M is [Ni _a Co _b Mn _(1-ab) ] _{1-c- d} Zr _c W _d ,

0.9? X? 1.5, 0.9? Y? 1.1, 0.4? A? 0.8, 0 <b? 0.4, 0 <c? 0.01, and 0 <d?

The metal oxide represented by the formula (1) may be a nickel-rich oxide, and in this case, 0.6? A? 0.8 in the formula (1).

The coating layer may be included in an amount of 0.001 to 0.01 mole per 1 mole part of the metal oxide.

The particle size of the cathode active material for the lithium secondary battery may be 5 탆 to 15 탆.

The cathode active material for the lithium secondary battery may be spherical.

The tap density of the cathode active material for the lithium secondary battery may be 2 to 3 g / ml.

The specific surface area of the cathode active material for the lithium secondary battery may be 0.2 to 0.7 m ² / g.

According to another embodiment of the present invention, there is provided a method for preparing a metal oxide, Adding a metal oxide and an aluminum compound of the following formula (1) to a solvent and mixing them; Drying the mixture of steps; And heat treating the dried mixture. The present invention also provides a method for producing a cathode active material for a lithium secondary battery.

[Chemical Formula 1]

Li _x M _y O ₂

Wherein M is represented by [Ni _a Co _b Mn _(1-ab) ] _{1-c- d} Zr _c W _d , 0.9? X? 1.5, 0.9? Y? 1.1, 0.4? A? 0.8, 0 <b ? 0.4, 0 < c? 0.01, and 0 < d?

The step of preparing the metal oxide of Formula 1 may include: preparing an aqueous metal salt solution containing a lithium source, a nickel source, a cobalt source, a manganese source, a zirconium source, and a tungsten source; Pulverizing the aqueous metal salt solution; Spray-drying the pulverized metal salt aqueous solution to prepare a metal oxide precursor; And heat treating the metal oxide precursor.

The step of pulverizing the metal salt aqueous solution may be performed such that the raw material particles have a particle size of 0.3 μm or less.

The particle size of the metal oxide precursor may be 5 탆 to 15 탆.

The step of heat-treating the metal oxide precursor may be performed at 860 to 890 ° C.

The step of heat-treating the metal oxide precursor may be performed for 24 to 36 hours.

In the step of adding the metal oxide and the aluminum compound of Formula 1 to a solvent and mixing them, the solvent may be an aqueous solvent, that is, water.

The aluminum compound may specifically be aluminum sulfate, aluminum nitrate, aluminum acetate, aluminum chloride, or a combination thereof.

The aluminum compound may be added in an amount of 0.001 to 0.01 mol based on 1 mol of the metal oxide of the formula (1).

The step of adding the metal oxide and the aluminum compound of Formula 1 to the solvent and mixing may be performed for 1 minute to 60 minutes.

The step of heat-treating the dried mixture may be performed at 550 ° C to 750 ° C.

According to another embodiment of the present invention, there is provided a lithium secondary battery including the positive electrode, the negative electrode, and the electrolyte containing the positive electrode active material.

Other details of the embodiments of the present invention are included in the following detailed description.

The positive electrode active material according to one embodiment and the lithium secondary battery including the same have excellent charge / discharge characteristics and life characteristics.

1 is a scanning electron microscope (SEM) photograph of the cathode active material prepared in Example 1. FIG.
FIG. 2 is a graph showing life characteristics of the batteries of Examples 1 to 3; FIG.
Fig. 3 is a graph showing life characteristic evaluations for the batteries of Examples 4 to 8. Fig.
4 is a graph showing the life characteristics of the battery of Comparative Example 1;
5 is a graph showing the life characteristics of the battery of Comparative Example 2;
6 is a graph showing the life characteristics of the battery of Comparative Example 3;

Hereinafter, embodiments of the present invention will be described in detail. However, the present invention is not limited thereto, and the present invention is only defined by the scope of the following claims.

An embodiment of the present invention includes a metal oxide represented by the following Chemical Formula 1 and a coating layer positioned on the surface of the metal oxide, wherein the coating layer is made of a metal selected from the group consisting of aluminum, aluminum oxide, lithium aluminum oxide, A cathode active material for a secondary battery is provided.

[Chemical Formula 1]

Li _x M _y O ₂

Wherein M is represented by [Ni _a Co _b Mn _(1-ab) ] _{1-c- d} Zr _c W _d , 0.9? X? 1.5, 0.9? Y? 1.1, 0.4? A? 0.8, 0 <b ? 0.4, 0 < c? 0.01, and 0 < d?

The cathode active material may be a lithium nickel cobalt manganese oxide doped with zirconium (Zr) and tungsten (W) in a predetermined amount, and aluminum, aluminum oxide, and / or lithium aluminum oxide may be coated on the surface thereof.

The positive electrode active material is excellent in charge / discharge characteristics, life characteristics, rate characteristics, stability and the like.

In the above formula (1), x is the molar ratio of Li and t is the molar ratio of M. The molar ratio x of lithium is 0.9? X? 1.5, and specifically 0.9? X? 1.4, 0.9? X? 1.3, 0.9? X? 1.2.

The M may be a transition metal, and may include nickel, cobalt, manganese, zirconium, and tungsten. M is specifically expressed as [Ni _a Co _b Mn _(1-ab) ] _{1-c- d} Zr _c W _d .

Where a is the molar ratio of nickel, b is the molar ratio of cobalt, c is the molar ratio of zirconium, and d is the molar ratio of tungsten.

The molar ratio of nickel is 0.4? A? 0.8. For example, the metal oxide represented by Formula 1 may be a nickel-based oxide, and 0.5? A? 0.8, 0.55 a? 0.8, and 0.6 a? 0.8. When the content of nickel satisfies the above range, high rate charge / discharge characteristics and high output characteristics of the battery can be realized. In particular, the higher the nickel content, the higher the energy density and the better the price.

The molar ratio of cobalt is 0 < b? 0.4, specifically 0 < b? 0.3, 0.1? B? 0.4 and 0.1? B? 0.3.

Within the ranges of a and b above, the ratio of nickel, cobalt and manganese can be suitably controlled.

0 < c < = 0.001, 0.00 < 0.003? C? 0.007. In this case, the cathode active material may exhibit excellent battery characteristics.

The content of tungsten may be 0 <d? 0.005, specifically 0? D? 0.004, 0? D? 0.003, 0.0005? D? 0.005, 0.0006? D? 0.004, and 0.0007? D? In this case, the cathode active material may exhibit excellent battery characteristics.

The coating layer may be contained in an amount of 0.001 to 0.01 mole per 1 mole of the metal oxide represented by the general formula (1). When the content of the coating layer satisfies the above range, the charge / discharge characteristics and life characteristics of the battery can be improved.

The cathode active material can improve charge / discharge characteristics, life characteristics, etc. of the battery by using zirconium and tungsten.

The cathode active material for a lithium secondary battery according to claim 1, wherein the cathode active material for lithium secondary batteries has a particle size of 5 탆 to 15 탆, specifically 6 탆 to 15 탆, 7 탆 to 15 탆, 8 탆 to 15 탆, 9 탆 to 15 탆, 10 탆 to 15 탆, Mu] m. When the particle size of the cathode active material satisfies the above range, the cathode active material can exhibit excellent battery characteristics.

The particle size of the cathode active material may mean D50, and D50 means a particle size at 50% by volume ratio in a cumulative size-distribution curve.

The cathode active material for the lithium secondary battery may be spherical. The coating layer may be continuously or discontinuously formed on the surface of the spherical metal oxide, and the final shape of the coated cathode active material may be spherical. In this case, the positive electrode active material can realize excellent battery characteristics.

The tap density of the cathode active material for the lithium secondary battery may be 2 to 3 g / ml, specifically 2.1 to 3 g / ml, 2.2 to 3 g / ml, 2 to 2.9 g / ml, and 2 to 2.8 g / ml. The cathode active material satisfies the tap density in the above range, which is advantageous in the production of electrodes and can increase the loading amount of the electrode plate to increase the energy density of the battery.

The specific surface area of the positive electrode active material for a lithium secondary battery may be 0.2 to 0.7 m ² / g, specifically 0.25 to 0.7 m ² / g, 0.3 to 0.7 m ² / g, and 0.4 to 0.7 m ² / g. The positive electrode active material satisfies the specific surface area in the above range and is advantageous in the life characteristic portion of the battery.

The specific surface area means a BET (Bnauer-Emmett-Teller) specific surface area.

According to another embodiment of the present invention, there is provided a method for preparing a metal oxide, Adding a metal oxide and an aluminum compound of the following formula (1) to a solvent and mixing them; Drying the mixture of steps; And heat treating the dried mixture. The present invention also provides a method for producing a cathode active material for a lithium secondary battery.

[Chemical Formula 1]

Li _x M _y O ₂

Wherein M is represented by [Ni _a Co _b Mn _(1-ab) ] _{1-c- d} Zr _c W _d , 0.9? X? 1.5, 0.9? Y? 1.1, 0.4? A? 0.8, 0 <b ? 0.4, 0 < c? 0.01, and 0 < d?

A metal oxide represented by Chemical Formula 1 and a coating layer disposed on a surface of the metal oxide, wherein the coating layer is made of a material selected from the group consisting of aluminum, aluminum oxide, lithium aluminum oxide, A cathode active material for a secondary battery can be produced.

The positive electrode active material is excellent in charge / discharge characteristics, life characteristics, rate characteristics, stability and the like.

A detailed description of the formula 1 is the same as described above.

First, the step of preparing the metal oxide of formula (1) will be described in detail.

The step of preparing the metal oxide of Formula 1 may include: preparing an aqueous metal salt solution containing a lithium source, a nickel source, a cobalt source, a manganese source, a zirconium source, and a tungsten source; Pulverizing the aqueous metal salt solution; Spray-drying the pulverized metal salt aqueous solution to prepare a metal oxide precursor; And heat treating the metal oxide precursor.

The lithium source may be, for example, lithium carbonate, lithium hydroxide, lithium nitrate, lithium oxide, or a combination thereof.

The nickel source may be, for example, a nickel sulfate salt, a nickel nitrate salt, a nickel chloride salt, a nickel acetate salt, or a combination thereof.

The cobalt raw material may be a cobalt sulfate cobalt salt, a cobalt nitrate salt, a cobalt hydrochloride salt, a cobalt acetate salt, or a combination thereof.

The manganese raw material may be manganese sulfate, manganese nitrate, manganese hydrochloride, manganese nitrate, or a combination thereof.

The zirconium source may be zirconium tetrachloride (ZrCl ₄ ) , zirconium sulfate, zirconium hydroxide (Zr (OH) ₄ ), or combinations thereof.

The tungsten raw material may be tungsten trioxide (WO ₃ ), ammonium paratungstate (APT; (NH ₄ ) ₁₀ W ₁₂ O ₄₁ .5H ₂ O), or a combination thereof.

This is an example of raw materials for each metal, but is not limited thereto.

The step of pulverizing the metal salt aqueous solution may be carried out, for example, by pulverizing using a bead mill.

Also, the step of pulverizing the metal salt aqueous solution may be performed such that the particle diameters of the raw materials are 0.3 μm or less. In this case, the spray drying step as the next step can be effectively performed.

The metal oxide precursor obtained by spray drying the pulverized metal salt aqueous solution may have a particle diameter of 5 to 15 탆. Specifically, the particle size of the metal oxide precursor may be 6 탆 to 15 탆, 7 탆 to 15 탆, 8 탆 to 15 탆, 9 탆 to 15 탆, 10 탆 to 15 탆, and 8 탆 to 14 탆. In this case, a cathode active material having a particle diameter of 5 탆 to 15 탆 and a good particle size distribution can be effectively produced.

The particle size of the metal oxide precursor may mean D50.

The step of heat-treating the metal oxide precursor may be performed at 860 to 890 ° C. Also, the step of heat-treating the metal oxide precursor may be performed for 24 to 36 hours. In this case, the metal oxide represented by Chemical Formula 1 can be effectively produced, and the cathode active material containing the metal oxide can realize excellent battery characteristics.

Hereinafter, a process of coating aluminum oxide or the like on the metal oxide represented by Chemical Formula 1 will be described.

In the method of preparing a cathode active material according to one embodiment, a water-based coating method is used as a coating method. In this case, an environmentally friendly aqueous solvent can be used without using an organic solvent. That is, in the step of adding the metal oxide and the aluminum compound of Formula 1 to the solvent and mixing them, the solvent may be water. In this case, it has the advantage of being environmentally friendly.

The aluminum compound used as the coating raw material may specifically be aluminum sulfate, aluminum nitrate, aluminum acetate, aluminum chloride, or a combination thereof.

The aluminum compound may be added in an amount of 0.001 to 0.01 mol based on 1 mol of the metal oxide of the formula (1). In this case, the charge / discharge characteristics, lifetime characteristics and the like of the battery can be improved.

The step of adding the metal oxide and the aluminum compound of Formula 1 to the solvent and mixing may be performed for 1 minute to 60 minutes. That is, the coating time may be from 1 minute to 60 minutes. Specifically, the coating time may be from 1 minute to 30 minutes, from 1 minute to 20 minutes, from 1 minute to 15 minutes, from 1 minute to 10 minutes, from 1 minute to 5 minutes. In this case, the coating layer can be effectively formed, and the cathode active material containing the cathode active material can exhibit excellent battery characteristics.

After the mixture of the metal oxide of formula (1), the aluminum compound and the solvent is prepared, the step of drying the mixture to remove the solvent is carried out. The drying step may be performed at 100 ° C to 200 ° C.

The dried mixture is subjected to a heat treatment (firing) at 550 ° C to 750 ° C. The firing temperature may specifically be 550 to 700 ° C, 550 to 650 ° C. In this case, it is possible to produce a positive electrode active material in which a coating layer is effectively formed.

The step of heat-treating the dried mixture may be performed for 5 to 15 hours. In this case, the coating layer can be effectively formed.

The coating layer thus formed appears to mainly contain aluminum oxide. Also, lithium present on the surface of the metal oxide of Formula 1 diffuses into the coating layer, and the coating layer is also considered to include lithium aluminum oxide.

The positive electrode active material may include a coating layer made of aluminum, aluminum oxide, and / or lithium aluminum oxide to achieve excellent battery characteristics.

According to another embodiment of the present invention, there is provided a lithium secondary battery including the positive electrode, the negative electrode, and the electrolyte containing the positive electrode active material.

The positive electrode includes a current collector and a positive electrode active material layer formed on the current collector.

Al may be used as the current collector, but the present invention is not limited thereto.

The cathode active material layer includes a cathode active material, a binder, and optionally a conductive material.

The binder may be selected from, for example, polyvinyl alcohol, carboxymethylcellulose, hydroxypropylcellulose, diacetylcellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polymers comprising ethylene oxide, Styrene-butadiene rubber, acrylated styrene-butadiene rubber, epoxy resin, nylon, and the like can be used.

The conductive material is used for imparting conductivity to the electrode. Any conductive material can be used without causing any chemical change in the battery. Examples of the conductive material include metal powders such as natural graphite, artificial graphite, carbon black, acetylene black, ketjen black, carbon fiber, copper, nickel, aluminum and silver, metal fibers and the like, and conductive materials such as polyphenylene derivatives May be used alone or in combination.

The negative electrode includes a current collector and a negative electrode active material layer formed on the current collector.

The current collector may be a copper foil, a nickel foil, a stainless steel foil, a titanium foil, a nickel foil, a copper foil, a polymer substrate coated with a conductive metal, or a combination thereof.

The negative electrode active material layer includes a negative electrode active material, a binder composition, and / or a conductive material.

The negative electrode active material includes a material capable of reversibly intercalating / deintercalating lithium ions, a lithium metal, an alloy of lithium metal, a material capable of doping and dedoping lithium, or a transition metal oxide.

Descriptions of the negative electrode active material, the binder composition and the conductive material will be omitted.

The electrolyte includes a non-aqueous organic solvent and a lithium salt. The non-aqueous organic solvent and the lithium salt can be used as long as they are compatible with each other, so that detailed explanation is omitted.

Hereinafter, examples and comparative examples of the present invention will be described. The following examples are only illustrative of the present invention and are not intended to limit the scope of the present invention.

Example  One

(1) Preparation of cathode active material

In order to prepare the metal oxide precursor, Li ₂ CO ₃ , Ni (OH) ₂ , Co (OH) ₂ , Mn ₃ O ₄ , Zr (OH) ₄ and WO ₃ as raw materials are weighed and dispersed in distilled water. The dispersed slurry is pulverized to a small particle size (Dmax = 0.3 μm or less) using a zirconium bead mill. The pulverized slurry is synthesized as a metal oxide precursor by using a spray dryer. The average particle diameter (D50) of the synthesized metal oxide precursor is 5 占 퐉 to 15 占 퐉.

1.5 kg of the synthesized metal oxide precursor was charged in a saggar of mullite and then sintered in an air atmosphere in a sintering furnace at a sintering temperature of 870 to 890 ° C and a sintering temperature of 2.85 ° C / do. Sintered for a total of 30 hours at a temperature of 7 hours, a holding time of 10 hours, a cooling time of 2.5 hours, a holding time of 5 hours and a cooling time of 6 hours.

The sintered material was pulverized and classified to obtain lithium nickel cobalt manganese composite metal oxide Li _1.05 (Ni _0.65 Mn _0.175 Co _0.175 ) _0.994 Zr _0.005 W _0.001 O ₂ .

The metal oxide was dispersed in an aqueous solution of 0.005 mol of aluminum nitrate (Al (NO ₃ ) ₃ ) at room temperature and coated for 10 minutes. Thereafter, the mixture was subjected to solid / liquid separation using a filter press, and residual moisture on the surface of the active material was removed using a high-pressure fresh air.

The active / liquid separated active material was dried using a fluid bed dryer at 150 ° C.

3 kg of the dried active material was filled in a saggar of mullite and then fired in a heat treatment furnace at a heat treatment temperature of 550 to 750 ° C at a heating rate of 2.85 ° C / min. Heat for 3 hours, 5 hours and 2 hours for 10 hours.

The aluminum surface-treated active material was pulverized and classified to obtain Li _1.00 (Ni _0.65 Mn _0.175 Co _0.175 ) _0.994 Zr _0.005 W _0.001 Al _0.005 O ₂ .

The physical properties of the synthesized cathode active material are shown in Table 1 below.

D50 (占 퐉) Tap density (g / ml) Specific surface area (m ² / g) Example 1 12.08 2.23 0.7

(2) Lithium secondary battery ( Half - cell )

The mixture was homogeneously mixed in a N-methyl-2-pyrrolidone solvent such that the mass ratio of the cathode active material, the conductive material (Denka black) and the binder (PVDF) was 92: 4: 4. The mixture was uniformly applied to an aluminum foil, compressed by a roll press, and vacuum-dried in a vacuum oven at 100 캜 for 12 hours to prepare a positive electrode.

A half-coin cell was prepared according to a conventional manufacturing method using Li-metal as a counter electrode and 1 mol of LiPF ₆ solution as a liquid electrolyte in a mixed solvent of EC: EMC = 1: 2 as an electrolyte solution. Respectively.

Example  2

A cathode active material was synthesized and a battery was prepared in the same manner as in Example 1 except that 0.01 mol of aluminum nitrate was coated.

Example  3

A cathode active material was synthesized and a battery was prepared in the same manner as in Example 1, except that 0.001 mol of aluminum nitrate was coated.

Example  4 to 8

The cathode active material was synthesized in the same manner as in Example 1 except that the coating time was set to 2 minutes, 5 minutes, 15 minutes, and 30 minutes and 60 minutes, respectively, to prepare a battery.

Comparative Example  One

A battery was fabricated in the same manner as in Example 1, except that Li _1.05 (Ni _0.65 Mn _0.175 Co _0.175 ) _0.994 Zr _0.005 W _0.001 O ₂ , which is a metal oxide not subjected to aluminum surface treatment in Example 1, was used as a cathode active material .

Comparative Example  2

The metal oxide Li _{1 .05} Ni _{0 .65} Mn _{0 .175} Co _{0 .175} O ₂ , in which Zr and W were not doped, was used without using the zirconium raw material and the tungsten raw material in the production of the precursor in Example 1, A cathode active material treated with an aluminum surface was used as in Example 1. That is used to _{Li 1 .00 Ni 0 .65 Mn 0} .175 Co 0 .175 Al 0 .005 O 2 as the positive electrode active material. The cell was prepared in the same manner as in Example 1.

Comparative Example  3

A battery was produced in the same manner as in Example 1, except that Li _1.05 Ni _0.65 Mn _0.175 Co _0.175 O _2, which was not doped with Zr and W and was not surface-treated with aluminum, was used as a cathode active material.

Evaluation example  1: Scanning electron microscope photograph of cathode active material

A scanning electron microscope (SEM) photograph of the cathode active material prepared in Example 1 is shown in FIG.

Referring to FIG. 1, it can be seen that a cathode active material having a particle diameter of about 5 to 15 μm and a uniform particle size distribution was produced.

Evaluation example  2: Evaluation of life characteristics

FIG. 2 is a graph showing life characteristics of the batteries of Examples 1 to 3; FIG.

Fig. 3 is a graph showing life characteristic evaluations for the batteries of Examples 4 to 8. Fig.

FIG. 4 is a graph showing the life characteristics of the battery of Comparative Example 1, and FIG. 5 is a graph showing life characteristics of the battery of Comparative Example 2. 6 is a graph showing the life characteristics of the battery of Comparative Example 3;

Referring to FIGS. 2 to 6, it can be seen that the batteries of Examples 1 to 9 have improved life characteristics as compared with the batteries of Comparative Examples 1 to 3.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the following claims. As will be understood by those skilled in the art. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive.

Claims (20)

A metal oxide represented by the following formula (1), and
And a coating layer disposed on a surface of the metal oxide,
Wherein the coating layer comprises aluminum, aluminum oxide, lithium aluminum oxide, or a combination thereof.
[Chemical Formula 1]
Li _x M _y O ₂
In the above formula (1), M is [Ni _a Co _b Mn _(1-ab) ] _{1-c- d} Zr _c W _d ,
0.9? X? 1.5, 0.9? Y? 1.1, 0.4? A? 0.8, 0 <b? 0.4, 0 <c? 0.01, and 0 <d? The method of claim 1,
Wherein in Formula 1, 0.6? A? 0.8, the cathode active material for lithium secondary batteries is 0.6? A? 0.8. The method of claim 1,
Wherein the coating layer is contained in an amount of 0.001 to 0.01 mole per 1 mole of the core. The method of claim 1,
Wherein the positive electrode active material for lithium secondary batteries has a particle diameter of 5 탆 to 15 탆. The method of claim 1,
Wherein the positive electrode active material for a lithium secondary battery is a spherical positive electrode active material for a lithium secondary battery. The method of claim 1,
Wherein the tap density of the cathode active material for the lithium secondary battery is 2 to 3 g / ml. The method of claim 1,
Wherein the specific surface area of the positive electrode active material for the lithium secondary battery is 0.2 to 0.7 m ² / g. Preparing a metal oxide represented by Formula 1 below;
Adding a metal oxide and an aluminum compound of the following formula (1) to a solvent and mixing them;
Drying the mixture of steps; And
Heat treating the dried mixture;
: &Lt; / RTI &gt; a method for producing a cathode active material for a lithium secondary battery comprising:
[Chemical Formula 1]
Li _x M _y O ₂
In the above formula (1), M is [Ni _a Co _b Mn _(1-ab) ] _{1-c- d} Zr _c W _d ,
0.9? X? 1.5, 0.9? Y? 1.1, 0.4? A? 0.8, 0 <b? 0.4, 0 <c? 0.01, and 0 <d? 9. The method of claim 8,
The step of preparing the metal oxide of the formula (1)
Preparing a metal salt aqueous solution containing a lithium source, a nickel source, a cobalt source, a manganese source, a zirconium source, and a tungsten source;
Pulverizing the aqueous metal salt solution;
Spray-drying the pulverized metal salt aqueous solution to prepare a metal oxide precursor; And
And heat treating the metal oxide precursor. The method for producing a cathode active material for a lithium secondary battery according to claim 1, The method of claim 9,
Wherein the pulverizing the metal salt aqueous solution is carried out by pulverizing the raw material so that the particle diameters of the raw materials are 0.3 mu m or less. The method of claim 9,
Wherein the metal oxide precursor has a particle diameter of 5 to 15 占 퐉. The method of claim 9,
Wherein the step of heat-treating the metal oxide precursor is performed at 860 to 890 캜. The method of claim 9,
Wherein the heat treatment of the metal oxide precursor is performed for 24 to 36 hours. 9. The method of claim 8,
A method for producing a cathode active material for a lithium secondary battery, wherein the solvent is water, wherein the metal oxide and the aluminum compound of Formula 1 are added to and mixed with a solvent. 9. The method of claim 8,
Wherein the aluminum compound is aluminum sulfate, aluminum nitrate, aluminum acetate, aluminum chloride, or a combination thereof. 9. The method of claim 8,
Wherein the aluminum compound is added in an amount of 0.001 to 0.01 mole per 1 mole of the metal oxide of the formula (1). 9. The method of claim 8,
Wherein the step of adding the metal oxide and the aluminum compound of Formula 1 to the solvent and mixing is performed for 1 minute to 60 minutes. 9. The method of claim 8,
Wherein the step of heat-treating the dried mixture is performed at 550 to 750 ° C. 9. The method of claim 8,
Wherein the heat treatment of the dried mixture is performed for 5 to 10 hours. A positive electrode comprising the positive electrode active material according to any one of claims 1 to 7,
Cathode, and
A lithium secondary battery comprising an electrolytic solution.

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